حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا عَبِيدَةُ بْنُ حُمَيْدٍ الْحَذَّاءُ، عَنِ الرُّكَيْنِ بْنِ الرَّبِيعِ، عَنْ حُصَيْنِ بْنِ قَبِيصَةَ، عَنْ عَلِيٍّ، - رضى الله عنه - قَالَ كُنْتُ رَجُلاً مَذَّاءً فَجَعَلْتُ أَغْتَسِلُ حَتَّى تَشَقَّقَ ظَهْرِي فَذَكَرْتُ ذَلِكَ لِلنَّبِيِّ صلى الله عليه وسلم - أَوْ ذُكِرَ لَهُ - فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ لاَ تَفْعَلْ إِذَا رَأَيْتَ الْمَذْىَ فَاغْسِلْ ذَكَرَكَ وَتَوَضَّأْ وُضُوءَكَ لِلصَّلاَةِ فَإِذَا فَضَخْتَ الْمَاءَ فَاغْتَسِلْ ‏"‏ ‏.‏

Narrated Abdullah ibn Sa'd al-Ansari

I asked the Messenger of Allah (ﷺ) as to what makes it necessary to take a bath and about the (prostatic) fluid that flows after taking a bath. He replied: that is called madhi (prostatic fluid). It flows from every male. You should wash your private parts and testicles because of it and perform ablution as you do for prayer.